1. Field of the Invention
This invention relates to a brush holder used for contacting a brush with a commutator and supplying a power to an armature, for example, in an electric motor.
2. Description of the Prior Art
As a conventional brush holder, there has been used a brush holder as shown in FIG. 3 and FIG. 4 for example.
A brush holder 104 shown in the figures is made of thin metallic plate and supports a brush 103 in a holding part 105 thereof so as to contact the brush 103 with a commutator 102 provided to an armature 101 of an electric motor shown in FIG. 3.
The brush holder 104 is provided with an opening 105a cut out rectangularly in a plane part 104a thereof for inserting a projection 103b sticking out from a contacting part 103a of the brush 103, and is provided with two holder piece 105b's protruding bendingly toward the center portion from side edges 104b and 104c of the plane part 104a in symmetry. And the opening 105a and the two holder piece 105b's form the holding part 105.
As shown in FIG. 4, the projection 103b of the brush 103 is inserted into the opening 105a of the holding part 105 from the lower side in the figure and the contacting part 103a of the brush 103 is contacted with the plane part 104a of the brush holder 104. And the brush holder 104 is so designed as to support the brush 103 in the holding part 105 by pinching the projection 103b of the brush 103 from both sides with the holder piece 105b's.
The brush holder 104 is fixed to a holder base (not shown) at the opposite end of the holding part 105, and energizes the brush 103 so as to contact the contacting part 103b with the commutator 102 by elasticity thereof.
Supplying an electric current to the armature 101 through the commutator 102 from a wire connected to the brush 103 or the brush holder 104, the armature 101 rotates, for example, in the direction of the arrow shown in FIG. 3.
However, in the aforementioned conventional brush holder 104, the brush 103 is holded in the holding part 105 of the brush holder 104 by pinching the projection 103b between the holder piece 105b's, accordingly the brush 103 is so supported as not to move in the vertical direction in FIG. 3, that is in the direction prependicularly intersecting the rotational direction of the armature 101, but may move side to side in FIG. 3, that is in the direction corresponding to the rotational direction of the armature 101. Therefore, there is a problem in quality of the motor since the projection 103b of the brush 103 moves in the opening 105a of the brush holder 104 according to the rotation of the aramture 101, and objectionable noise and vibration appear owing to the hit between the brush 103 and the brush holder 104.